To george s



(No Model.)

J. B. WORTHAM.

SYRINGE PISTON.

No. 282,144. Patented July 31. 1883..

N. PEYERS. Phowmhn m hu, Washmglnn. D. C.

UNITED STATES PATENT OFFICE.

JOHN B. WORTHAM, on WINCHESTER, VIRGINIA, nests-Non or ONE-HALF TO GEORGE s. CRANE, OF SAME PLACE.

SYRINGE-PISTON.

SPECIFICATION forming part of Letters Patent No. 282,144, dated July 31, I883.

Application filed 'May 25, 1883. (No model.)

To to whom it may concern Be it known that I, JOHN B. WVORTHAM, a citizen of the United States, residing at Winchester, in the county of Frederick, and State of Virginia, have invented certain new and useful Improvements in Pistons, of which the following is a full, clear, and exact description.

This invention has for its object the provision of an anti-regurgitating expansible piston, adapted to be operated while within the working-cylinder, and without removal therefrom,

from outside said cylinder.

Before my invention pistons have been variouslyconstructed to render them expansiblaas, for example, by makingthem of elastic material adapted to be spread it by an adjustable I conical rod; and such a piston has been arranged upon a tube through which and the piston the conical rod projects and is operable cxteriorly of the cylinder without removal of the piston therefrom. Regurgitationhas been prevented,in a measure, at least, by constructing the piston of reversed cups; but no provision has been made in such pistons for compensatin g by adjustment or expansion for wear, and for insuring a tight or close fit of the piston in its cylinder.

Referring to a single application of my invention, the piston of a hypodermic syringe must fit its cylinder with great accuracy in order to discharge the full quantity of the small contents of the syringe, and" such a piston must be capable-of a very ready adjustment to insure such fit; and stating my invention with reference to such a use thereof, it

' consists of a piston composed of reversed cups of leather or equivalent flexible, soft, yielding material expansible under the action of a conical tube adjustable on the pisto nrod, and constructed and arranged as hereinafter specifically set forth and claimed, to insure an accurate fit of the piston in the cylinder and prevent regurgitation of the liquid to be injected.

In the accompanying drawings, in the several figures of which likeparts are similarly designated, Figure 1 is a perspective view of the piston, rod, adjusting or expanding tube, and cylinder-cap detached, illustrating my invention. Fig. 2 is a perspective view ofthe adjusting or expanding tube; Fig. 3, a per-,

spective view of the piston-rod; Fig. 4, a per speetive View of the upper member of the pis ton; Fig. 5, a perspective view of the lower member of the piston;.Fig. 6, a perspective view of the nutto hold the piston 'to its rod; 5 Figs. 7 and 8, perspective views of the 'cap and body or cylinder of a hypodermic syringe.

Fig. 9 is a longitudinal section, enlarged, of a hypodermic syringe (the needle being omitted) illustrating one application of my invention, 6 and Figs. 10 and 11 perspective views of other forms of the upper member of the piston.

The letter a designates ascrew-threaded rod extending through an interiorly screw-threaded tube, 1), which is adjustable or movable 1011- 6 gitudinally upon said rod by engagement with its thread, and for convenience in effecting such adjustment said tube may have a milled head, 0, by which it may be rotated. The exterior of the tube bis smooth and adapted to fit a V cap, gland, or box, (I, of a working-cylinder or pump-barrel, e, for the piston. The rod a and the tube b jointly constitute the piston-rod, and suitable provision, as a button or knob, f, is made for reciprocating said rod in its cylinder. The lower end of the rod a is shouldered at g, and below said shoulder is preferably reduced in diameter and threaded at 71 The lower end of the tube 1) is made conical,

or provided with a wedge, (he rein designated The upper member, is, of my piston is a rectangular or equivalent bit of leather or like soft flexible substantially inelastic material,

.perforated to fit on the screw 71, up against the 8 5 shoulder 9, around which and the rod it is shaped or molded into essentially a split tube, one end (the lower) being closed, (against the shoulder 5 and the other (the uppermost) being open. The lower auxiliary or working- 0 face member, Z, of the piston is a smaller reversed cup or tube, which may be out and shaped of sole-leather, and is secured upon the screw it, with its base against the closed end of member k, by a nut, m, within, inclosed 5 or surrounded by it.

Any expansion of a piston at its lower end which would tend to increase the diameter and circumference of the lower part with a gradually-diminishingdiameterupward would too have the effect of badly binding the piston as it is projected to discharge the contents of a Q sear m cylinder; but I find that the expansion of the piston in the exact opposite effects an easy projection of the piston without in the least dopreciating the tightness of fit necessary to insure the discharge of the contents, and at the same time completely curing or obviating that regurgitation common in many kinds of handpumps, syringes, and the like. I therefore arrange the cone or wedge 1' so as to be longitudinally adjustable on the stem or rod a, to be more or less inserted into the split tubelike upper member, k, of my piston to expand said piston initially from its top; but such expansion is never of so great an extent as to leave any material opening at the meeting edges of its sides. Now, the inverted cone formed in my piston by this upper member not only insures the proper discharge of the contents of the cylinder and prevents regurgitation, but it imparts an increased suctional action to the piston, as it insures tight fit in the barrel or cylinder.

The adjustment of the cone 1? for the expansion or contraction of the piston isefiected by the rotation of the tube bupon the rod a, which is performed outside the cylinder or barrel without removal of the piston.

The rod (1 and tube Z) may be threaded to the extent shown, or to a less extent, suflicient, however, to enable the cone or wedge to be in serted the required distance in the washer or piston member In Fig. 10 I have shown a preferred form of upper member or washer, is, it differing from that hereinbefore described in having its slits made diagonal, or the meeting edges beveled or skived, so as to overlap and thus insure the registering of these edges. This upper member of the piston may also be made as an uncut thimble without slits, as in Fig ll, and its expansion provided for by its elasticity, or quality of being stretched under the operation ofthe wedge.

hat I claim is 1. A piston composed of two inverted-cupshaped members placed base to base upon the piston-rod and secured thereon, combined with an adjustable wedge or cone movable within the upper member of said piston to expand said member, substantially as described.

2. The combination, substantially as shown and described, of a piston having a tube-like upper member, and a lower auxiliary member or working-face, witha rod or a stem to which they are secured, and a cone or wedge adjustable upon said rod or stem exteriorly of the barrel or working-cylinder, to vary the circumference or diameter of said-upper member.

3. The combination, substantially as shown and described, of a threaded rod or stem, a, shouldered at its lower end, and provided with a contracted threaded portion, h, an interiorlythreaded tube, b, arranged upon said rod, and provided with a cone or wedge at its lower end, and an operating device to rotate it upon the rod or stem and thereby adjust it longitudinally upon the same, and a two-part piston secured to said rod or stem,'with its upper part or member adapted to receive within it the cone or wedge of the adjustable tube 1), to

be by its adjustment varied in diameter, as and for the purpose specified.

In testimony whereof I have hereunto set my hand this 24th day of May, A. D. 1883. J. B. \VORTHAM. Vitnesses G. VVQGRIM, MEREDITH FORNEY. 

